JPH02246075A - File retrieval system in magnetic tape volume - Google Patents

Abstract

PURPOSE:To position a head at high speed by providing a file control information block in front of the BOT (tape top position) of magnetic tape volume, writing a file name and position information on it, and positioning the head by referencing them at the time of accessing. CONSTITUTION:A file control information block 1 is the block which stores the file name and position information (a physical block 1D and a logical block 1D) existing in the magnetic tape volume in front of the BOT. Since the position information executes rough high-speed searching, it consists of the physical block 1D having a value, which is counted up whenever the magnetic tape progresses by a prescribed distance, and the logical block 1D to be serial numbers applied to a data block and a data mark block with the BOT as a reference point. Thus by using the physical block 1D and the logical block 1D and using the high-speed searching function, the head can be positioned at the top of the corresponding file at high speed.

Description

[Detailed Description of the Invention] [Summary] Regarding a file search method for searching a file position in a magnetic tape volume, the present invention relates to a file search method for searching a file position in a magnetic tape volume.
A file management information block is provided before the file (Tape),
In order to quickly find the relevant location by referring to this, a file management information block that stores the name and location information of the file existing in the magnetic tape volume is provided before BOT, and a file is created in the magnetic tape volume. - When the contents of a file management information block change due to additions, etc., the contents of the file management information block are rewritten, and in response to an access instruction specifying either the file name, file sequence number, or both, B
The above file management information block located before 0T is searched, and when found, the head is positioned and accessed based on the extracted position information, while on the other hand, when it is not found, a notification to that effect is sent.

[Industrial application field]

The present invention relates to a file search method for searching file positions within a magnetic tape volume.

[Prior Art and Problems to be Solved by the Invention] Conventionally, the process of positioning a head to a file in a magnetic tape volume has been carried out in a manner that skips to the tape mark TM written on the magnetic tape as shown in FIG. It runs at high speed, reads the contents of the next block of tape mark TM, and if it is not the corresponding file, then it reads the contents of the next block of tape mark TM.
I kept repeating the process of skipping to M until I found the correct file. In this way, after skipping to the tape mark TM, the contents of the block were read and sequentially determined whether or not it was a corresponding file, which caused the problem that the corresponding position on the magnetic tape volume could not be found by searching at high speed. .

The present invention provides BOT (Big
A file management information block is provided before in (HTape), and the purpose is to quickly find the corresponding position by referring to this block.

[Means to solve problems]

Means for solving the problem will be explained with reference to FIG.

In FIG. 1, file management information block 1 is BO
This block stores name and position information (physical block ID and logical block 10) of files existing in the magnetic tape volume before T.

File management information block start display 2 is a display indicating the start position of the file management information block.
gin of tape) is the starting position at which data etc. are written on the magnetic tape.

[Effect]

As shown in FIG. 1, the present invention provides a file management information block l before BOT on a magnetic tape volume,
When the contents of file management information block 1 are changed by creating, adding, or updating a file on the magnetic tape volume, the file management information consisting of the file name and position information is written in the file management information block header display 2. Then, in response to an access instruction that specifies either the file name, file sequence number, or both, the file management information block l located before BOTO is searched, and if found, based on the retrieved position information. The head is positioned to access the file, and if it is not found, a notification to that effect is sent.

Therefore, the magnetic tape volume BOT (Bigi
File management information block 1 before nOf 7ape)
By providing a block 1 and writing the file name and position information therein, it is possible to refer to this file management information block 1 at the time of access and position the head at a corresponding position at high speed.

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be explained in detail using FIGS. 1 to 3.

In FIG. 1(a), file management information block 1 is a block that stores name and position information (physical block ID and logical block ID) of files existing in the magnetic tape volume before BOT. This position information consists of a physical block ID with a value that is incremented every time the magnetic tape advances a predetermined distance, and a serial number assigned to the data block and tape mark block with BOT as the base point, in order to perform a rough high-speed search. It consists of a logical block ID. Using both of these physical block IDs and logical block IDs and using a high-speed search function, it is possible to quickly position the head at the beginning of the corresponding file. Here, file management information block l includes the HDR1 label in the figure, EO
The physical block ID and logical block ID corresponding to the F2 label are respectively stored. Further, the file management information block 1 is written starting from the file management information block top display 2.

FIG. 1 (b) shows an example of a file management information block.
This is shown in Figure 1 (a) BOT on the magnetic tape volume.
EOF as the file name and position information that was written before the magnetic tape volume and exists within the magnetic tape volume.
2 label (plus HDR1 label) physical block ID,
The files are written in association with logical block IDs and arranged in the order of file sequence numbers. By referring to this file management information block 1, the file name, file sequence number, and position existing in the magnetic tape volume can be immediately found.

Next, the operation of the configuration of one embodiment of the present invention will be explained using FIG.

In FIG. 2, ■ inputs the file name (A).

This means that one or both of the file name and file order number to be searched must be entered.

■ is the file name (A) from the file management information block l.
).

O determines whether it is found.

If YES (found), execute [phase] to [phase]. If NO, press ■ to notify the access requester that the file does not exist and exit (EN
D).

[Phase] calculates the start address by adding the EOF2 label of the previous file name + 1.

(2) positions the head at the beginning of file (A).

[Phase] is accessed.

As described above, in response to an access instruction specifying a file name, it is possible to refer to the file management information block 1, extract the corresponding location information, and quickly locate and access the location.

Next, high-speed search processing will be explained using FIG. 3.

In Figure 3, ■ indicates the file management information block l that is transferred when the O8 requests the hardware to read file management information block 1 when the magnetic tape polynym is set (mounted) on the magnetic tape device. O
3 shows the process of pointing from the control table, in this case,
The hardware side that has received the processing request positions the head at the position of the file management information block header display 2, reads from the file management information block 1, and transfers it to the O8 side. In response to this transfer, O3 points to this file management information block from the O3 control table as shown.

■ indicates the search process executed by the application program when the magnetic tape volume is 0PEN. This search process was able to determine the position of the head based on the file management information block read in the process of ■. If so, use the fast search function to locate it. The high-speed search function is a function that quickly locates a general position based on the physical block ID described above and then further locates at a corresponding position based on the logical block ID. This positioning can be forward (BOT-EOT) or reverse (EOT-EOT).
→BOT) Positioning is possible in either direction.

(2) shows the update process at CLO3E of the magnetic tape volume after the head has been positioned at the appropriate position in (2), the data writing process from the application program has been completed, and this update process is completed by the process (2). If there is a change in the contents of the file management information block read in the process of ■ (when a file is created or data is added, etc.), update the contents of the file management information block pointed to from the O3 control table. .

■ indicates the process that runs when the execution of the application program is finished and the magnetic tape volume is demounted from the magnetic tape device. This process is read by the process of ■, and
This means that the file management information block updated in the process is written to a location on the magnetic tape volume. As a result, the contents of the file management information block 1 on the magnetic tape volume are rewritten. Furthermore, when the data cannot be stored in the file management information block 1 at the time of writing (when the erase head is caught in the BOT), the overflow of the file management information is notified to O3, and
Prevent data after BOT from being rewritten.

〔Effect of the invention〕

As explained above, according to the present invention, a file management information block l is provided before the BOT (Begin Of Tape) of a magnetic tape volume, a file name and position information are written in this block, and this is referenced at the time of access. Because it uses a configuration that determines the position of the head by
The head can be positioned quickly. Particularly, when a plurality of files exist on a magnetic tape polyneme, the head can be positioned at the beginning of the file at high speed. Furthermore, if a file does not exist on the magnetic tape polynym, this fact can be detected at high speed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a flowchart explaining the operation of the present invention, FIG. 3 is a diagram explaining high-speed search processing according to the present invention, and FIG. 4 is a diagram explaining the prior art. In the figure, l indicates the file management information block, 2 indicates the beginning of the file management information block, and BOT indicates Begin Of.
Tape (tape beginning position).

Claims (1)

[Claims] In a file search method for searching file positions in a magnetic tape volume, a file management information block (1) is provided before the BOT to store name and position information of files existing in the magnetic tape volume. , When the contents of the file management information block (1) are changed due to the creation or addition of a file to the magnetic tape volume, the contents of the file management information block (1) are rewritten and either the file name or the file sequence number is changed. In response to an access instruction specifying one or both, search the above file management information block (1) in front of BOT,
A file search method in a magnetic tape volume is characterized in that when a file is found, the head is positioned and accessed based on the retrieved position information, and on the other hand, when it is not found, a notification is sent to that effect.